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<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN"><!-- This collection of hypertext pages is Copyright 1995-2005 by Steve Summit. --><!-- Content from the book "C Programming FAQs: Frequently Asked Questions" --><!-- (Addison-Wesley, 1995, ISBN 0-201-84519-9) is made available here by --><!-- permission of the author and the publisher as a service to the community. --><!-- It is intended to complement the use of the published text --><!-- and is protected by international copyright laws. --><!-- The on-line content may be accessed freely for personal use --><!-- but may not be published or retransmitted without explicit permission. --><!-- --><!-- this page built Sat Dec 24 21:47:45 2005 by faqproc version 2.7 --><!-- from source file aryptr.sgml dated Wed Dec 21 12:50:38 2005 --><!-- corresponding to FAQ list version 4.0 --><html><!-- Mirrored from c-faq.com/aryptr/index.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:54:37 GMT --><head><meta name=GENERATOR content="faqproc"><title>Arrays and Pointers</title></head><body bgcolor="#ffffff"> <a href="../index-2.html"><img src="../images/buttontop.gif" alt="top/contents"></a><a href="../search.html"><img src="../images/buttonsrch.gif" alt="search"></a><hr><H1>6. Arrays and Pointers</H1><p><a href="aryptr1.html" rel=subdocument>6.1</a>I had the definition <TT>char a[6]</TT> in one source file, and inanother I declared <TT>extern char *a</TT>.Why didn't it work?</p><p><a href="aryptr2.html" rel=subdocument>6.2</a>But I heard that <TT>char a[]</TT> was identical to <TT>char *a</TT>.</p><p><a href="aryptrequiv.html" rel=subdocument>6.3</a>So what is meant by the ``equivalence of pointers and arrays'' in C?</p><p><a href="aryptrparam.html" rel=subdocument>6.4</a>If they're so different,thenwhyare array and pointer declarations interchangeable asfunction formal parameters?</p><p><a href="arypbref.html" rel=subdocument>6.4b</a>So arrays are passed by reference,even though the rest of C uses pass by value?</p><p><a href="arrayassign.html" rel=subdocument>6.5</a>Why can'tIdo something like this?<pre> extern char *getpass(); char str[10]; str = getpass("Enter password: ");</pre></p><p><a href="aryparmasgn.html" rel=subdocument>6.6</a>If you can't assign to arrays,thenhow can<pre> int f(char str[]) { if(str[0] == '\0') str = "none"; ... }</pre>work?</p><p><a href="aryasgn3.html" rel=subdocument>6.6b</a>And what about this?Isn't this an array assignment?<pre> char a[] = "Hello, world!\n";</pre></p><p><a href="arraylval.html" rel=subdocument>6.7</a>How can an array be an lvalue, if you can't assign to it?</p><p><a href="practdiff.html" rel=subdocument>6.8</a>Practically speaking,whatis thedifference between arrays and pointers?</p><p><a href="constptr.html" rel=subdocument>6.9</a>Someone explained to me that arrays were really just constant pointers.</p><p><a href="ptrkindofary.html" rel=subdocument>6.10</a>I'm still mystified.Is a pointer a kind of array,or is an array a kind of pointer?</p><p><a href="joke.html" rel=subdocument>6.11</a>I came across some ``joke'' code containing the ``expression''<TT>5["abcdef"]</TT> .How can this be legal C?</p><p><a href="aryvsadr.html" rel=subdocument>6.12</a>Since array references decay into pointers,if <TT>arr</TT> is an array,what'sthe difference between<TT>arr</TT> and <TT>&arr</TT>?</p><p><a href="ptrtoarray.html" rel=subdocument>6.13</a>How do I declare a pointer to an array?</p><p><a href="dynarray.html" rel=subdocument>6.14</a>How can I set an array's size at run time?<br>How can I avoidfixed-sized arrays?</p><p><a href="dynlocarys.html" rel=subdocument>6.15</a>How can I declare local arrays of a size matching a passed-in array?</p><p><a href="dynmuldimary.html" rel=subdocument>6.16</a>How can I dynamically allocate a multidimensional array?</p><p><a href="non0based.html" rel=subdocument>6.17</a>Here's a neat trick: if I write<pre> int realarray[10]; int *array = &realarray[-1];</pre>I can treat <TT>array</TT> as if it were a 1-based array.</p><p><a href="pass2dary.html" rel=subdocument>6.18</a>My compiler complained when I passed a two-dimensional array to afunction expecting a pointer to a pointer.</p><p><a href="ary2dfunc2.html" rel=subdocument>6.19</a>How do I write functions which accept two-dimensional arrayswhen the width is not known at compile time?</p><p><a href="ary2dfunc3.html" rel=subdocument>6.20</a>How can I use statically- and dynamically-allocatedmultidimensional arrays interchangeably when passing them to functions?</p><p><a href="aryparmsize.html" rel=subdocument>6.21</a>Why doesn't <TT>sizeof</TT> properly report the size of an arraywhen the arrayis a parameter to a function?I have a test routine<pre> f(char a[10]) { int i = sizeof(a); printf("%d\n", i); }</pre>and it prints4, not 10.</p><p><a href="extarysize.html" rel=subdocument>6.22</a>How can code in a file where an array is declared as <TT>extern</TT>(i.e. it is defined, and its size determined, in some other file)determine the size of the array?<TT>sizeof</TT> doesn't seem to work.</p><p><a href="arraynels.html" rel=subdocument>6.23</a>I want to know how many elements are in an array,but <TT>sizeof</TT> yields the size in bytes.</p><p><a href="arybits.html" rel=subdocument>6.24</a>Is there a way to have an array of bits?</p><hr><p><a href="../index-2.html">top</a></p><p><a href="../questions.html"><img src="../images/buttontop.gif" alt="contents"></a><a href="../search.html"><img src="../images/buttonsrch.gif" alt="search"></a><br><a href="../about.html">about this FAQ list</a> <a href="../eskimo.html">about eskimo</a> <a href="../search.html">search</a> <a href="../feedback.html">feedback</a> <a href="copyright.html">copyright</a><p>Hosted by<a href="http://www.eskimo.com/"><img src="../../www.eskimo.com/img/link/eskitiny.gif" alt="Eskimo North"></a></p></body><!-- Mirrored from c-faq.com/aryptr/index.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:54:48 GMT --></html>⌨️ 快捷键说明
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